Complementary un-registration of providers; change function name

include/audacity/ModuleInterface.h

@@ -164,12 +164,15 @@ static ModuleInterface * name(const wxString *path)
 // Provides the base for embedded module registration.  If used, a Register()
 // method must be supplied explicitly.
 // ----------------------------------------------------------------------------
+
 #define DECLARE_BUILTIN_MODULE_BASE(name)             \
 class name                                            \
 {                                                     \
 public:                                               \
    name() {Register();}                               \
+   ~name() {Unregister();}                            \
    void Register();                                   \
+   void Unregister();                                 \
 };                                                    \
 static name name ## _instance;
 
@@ -181,7 +184,11 @@ static name name ## _instance;
 DECLARE_BUILTIN_MODULE_BASE(name)                     \
 void name::Register()                                 \
 {                                                     \
-   RegisterBuiltinModule(MODULE_ENTRY);               \
+   RegisterProvider(MODULE_ENTRY);                    \
+}                                                     \
+void name::Unregister()                               \
+{                                                     \
+   UnregisterProvider(MODULE_ENTRY);                  \
 }
 
 #else

src/ModuleManager.cpp

@@ -182,13 +182,23 @@ namespace {
    }
 }
 
-void RegisterBuiltinModule(ModuleMain moduleMain)
+void RegisterProvider(ModuleMain moduleMain)
 {
-   builtinModuleList().push_back(moduleMain);
+   auto &list = builtinModuleList();
+   if ( moduleMain )
+      list.push_back(moduleMain);
 
    return;
 }
 
+void UnregisterProvider(ModuleMain moduleMain)
+{
+   auto &list = builtinModuleList();
+   auto end = list.end(), iter = std::find(list.begin(), end, moduleMain);
+   if (iter != end)
+      list.erase(iter);
+}
+
 // ----------------------------------------------------------------------------
 // Creation/Destruction
 // ----------------------------------------------------------------------------

src/ModuleManager.h

@@ -136,6 +136,13 @@ private:
 using ModuleMain = ModuleInterface *(*)(const wxString *path);
 
 AUDACITY_DLL_API
-void RegisterBuiltinModule(ModuleMain rtn);
+void RegisterProvider(ModuleMain rtn);
+AUDACITY_DLL_API
+void UnregisterProvider(ModuleMain rtn);
+
+// Guarantee the registry exists before any registrations, so it will
+// be destroyed only after the un-registrations
+static struct Init{
+   Init() { RegisterProvider(nullptr); } } sInitBuiltinModules;
 
 #endif /* __AUDACITY_MODULEMANAGER_H__ */